1. Field of the Invention
The present invention relates to mining systems and, more particularly, is directed toward a longwall mining system.
2. Description of the Prior Art
In a longwall coal mining system, a shearer having a cutting head with a plurality of picks disposed in a helical path about the head surface is traversed back and forth along the seam's face, cutting off a layer of coal during each traverse. The helically configured drum defines a screw conveyor which carries the coal from the face back toward a face conveyor. The cut coal, which is dropped onto the face conveyor by the auger action of the helically disposed picks, is carried to a main conveyor for hauling to the outside. In such systems, shields are provided to support the roof of the mine near the face in order to prevent collapse of the roof. U.S. Pat. No. 4,045,087 shows a longwall mining system roof support. Since the cut coal is merely dropped onto the face conveyor, it is necessary to position the face conveyor adjacent the shearer. Such longwall mining systems have suffered from the disadvantage that the face can be cut a minimal amount on each traverse. The depth of cut is limited because of the instability of the shearer and the inefficient loading techniques inherent in a helical head configuration. Since the cutting heads are supported from one end only on a cantalever arm, the heads are made narrow to minimize instability. The auger action of loading coal by dropping it onto the face conveyor produces excessive dust.